Anthony Stadlen has practised since 1971 as an existential-phenomenological psychotherapist in London. He is registered by both the British Confederation of Psychotherapists and the United Kingdom Council for Psychotherapy as a psychoanalytic psychotherapist, and by the United Kingdom Council for Psychotherapy as an existential psychotherapist. He has taught and supervised at the Association of Independent Psychotherapists, the London Centre for Psychotherapy, the New School of Psychotherapy and Counselling; and Regent's College School of Psychotherapy and Counselling.

Since 1979 he has conducted a research programme on the foundations of psychotherapy, sponsored by the Department of Philosophy, University of Essex, England, and supported by the Nuffield Foundation. He has investigated the paradigmatic case-studies of psychotherapy and analyses of dreams and parapraxes by Freud, Layard, Fordham, Boss, Laing and Esterson, and others. He has also investigated the collaboration of Boss and Heidegger on Daseinsanalysis, and the psychological techniques used by the Nazis to deceive and mystify their victims. He has lectured on this research in a number of countries.

Since April 1996, he has organised and conducted the Inner Circle Seminars, one Sunday a month, in London. They are an ethical, existential, phenomenological search for truth in psychotherapy, to which many distinguished international speakers from a number of disciplines have contributed, including Tom Greeves, David Harsent, Susannah Heschel, Sheila Kitzinger, Claudia Koonz, Malcolm Macmillan, Gitta Sereny, Sonu Shamdasani, Ann-Helen Siirala, Martti Siirala, David Singmaster, Richard Skues, Naomi Stadlen, Peter Swales, Thomas Szasz, Terry Tanner, Michael Tregenza.

Anthony Stadlen is an Honorary Visiting Fellow of Regent's College School of Psychotherapy and Counselling, London, and a former Honorary Research Fellow of the Freud Museum, London.